Metal-organic layers induce in situ nano-structuring of Cu surface in electrocatalytic CO2 reduction

Cu-based catalysts have attracted widespread attention for its capability in electrocatalytically reducing CO2 to a variety of products. Surface modification of Cu has become an interesting method for tuning the catalytic performance. Here, we use Zr-based metal-organic layers (MOLs) as the additive of the Cu surface, which enhanced the Faradaic efficiency of CH4 by two times as compared to the untreated polycrystalline Cu foil. Unexpectedly, the MOLs were found to induce in situ nano-structuring of the Cu foil surface within seconds in the electrolysis, as revealed by a combination of scanning electron microscopy (SEM), grazing incidence X-ray diffractometry (GIXRD), and linear sweep voltammetry (LSV) measurements. These surface changes are responsible for the shift of product selectivity. Control experiments suggest that negatively charged mu(3)-O- on the Zr-cluster in the MOL might interact with CO-covered Cu surface and induce roughing and nano-structuring. This work reveals a potential role of additive on Cu to induce surface nano-structuring that tunes catalytic activity and selectivity.